1. Field of the Invention
The present invention relates to a battery support structure for a vehicle that supports a battery pack in a lower part of a vehicle body, and more particularly to a structure with which both a crashable stroke relative to a side-on collision and a battery loading capacity are secured.
2. Description of the Related Art
A large amount of secondary batteries such as lithium ion batteries or nickel hydrogen batteries must be loaded in an electric vehicle such as an engine-electric hybrid vehicle, a plug-in hybrid vehicle, or an electric automobile.
The batteries are loaded in the vehicle in the form of a battery pack in which a plurality of battery cells are housed in a case.
Among respective constituent components of the vehicle, the battery pack has a comparatively large weight, and it has therefore been proposed that the battery pack be loaded in an interval between left and right side frames on a lower side of a floor panel forming a floor surface of a passenger compartment in order to lower a center of gravity position of the vehicle and thereby secure a favorable traveling performance and so on.
Japanese Unexamined Patent Application Publication (JP-A) No. H6-261422, for example, describes an electric automobile in which a battery pack is loaded in a region between left and right side frames of a lower part of a vehicle body under a floor panel.
In this type of battery pack, it is necessary to ensure that the case is not crushed even when the vehicle crashes in order to protect the battery cells.
As related art pertaining to a battery loading structure designed in consideration of a side-on collision, JP-A No. 2008-184015, for example, describes interposing a bracket between upper stage batteries and lower stage batteries so that the bracket can be restored in a flattening direction by the weight of the upper stage batteries.
When taking the performance of the vehicle during a side-on collision into consideration, it is important to secure a crashable stroke by causing the vehicle body to deform such that the side frame is pushed inward in a vehicle width direction, thereby absorbing energy.
When a clearance between the battery pack and the side frame is increased to secure an allowable amount of lateral direction displacement in the side frame, a maximum loadable capacity of the battery pack decreases, making it difficult to secure a battery capacity required to obtain a favorable performance in the vehicle.
In a case where it is difficult to secure a sufficient crashable stroke, the strength of components such as the side frames and side sills must be increased in order to absorb an input load, leading to increases in weight and cost and reductions in fuel efficiency and drivability.